The P5 protein from bacteriophage phi-6 is a distant homolog of lytic transglycosylases

Jimin Pei, Nick V. Grishin

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Peptidases are classical objects of enzymology and structural studies. However, a few protein families with experimentally characterized proteolytic activity, but unknown catalytic mechanism and three-dimensional structures, still exist. Using comparative sequence analysis, we deduce spatial structure for one of such families, namely, U40, which contains just one P5 protein from bacteriophage phi-6. We show that this singleton sequence possesses conserved sequence motifs characteristic of lysozymes and is a distant homolog of lytic transglycosylases that cleave bacterial peptidoglycan. The structure of the P5 protein is therefore predicted to adopt the lysozyme-like fold shared by T4, λ, C-type, G-type lysozymes, and lytic transglycosylases. Since previous biochemical experiments with P5 of phi-6 have indicated that the purified enzyme possesses endopeptidase activity and not glycosidase activity, our results point to the possibility of a newly evolved molecular function and call for further experimental characterization of this unusual P5 protein.

Original languageEnglish (US)
Pages (from-to)1370-1374
Number of pages5
JournalProtein Science
Issue number5
StatePublished - May 2005


  • Bacteriophage phi-6
  • Comparative phage genomics
  • Lysozyme
  • Lytic transglycosylase
  • Peptidase
  • Structure prediction

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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